Method and apparatus for processing of carbon-containing feed stock into gasification gas

ABSTRACT

The invention relates to chemical technology and equipment, in particular to apparatuses of processing of solid household and industrial waste, as well as other carbon-containing feedstock into combustible gasification gas and methods for pyrolysis and downdraft gasification process.

This application is a Divisional application of U.S. patent applicationSer. No. 13/042,220 and it claims the priority of U.S. ProvisionalPatent Application Ser. No. 61/314,002 filed on Mar. 15, 2010, which isincorporated herein by reference in its entirety herein.

The invention relates to chemical technology and equipment, inparticular, to processes and apparatuses for processing of solidhousehold and industrial waste, fossil fuels as well as othercarbon-containing feedstock into gasification gas by use of pyrolysisand downdraft gasification processes.

BACKGROUND

The downdraft gasification process has a number of advantages comparedto the updraft gasification process, which is the process typically usedin modern technologies for processing of carbon-containing feedstock.One such advantage of the downdraft gasification process is that processtars, acids and steam, which are formed in a low temperature pyrolysiszone, go through the combustion and reforming zones where, under theexposure to high temperatures, they reach almost a complete conversioninto gasification gases. This makes it possible to use said gases forproduction of electric energy in gas-diesel engines, gas powered enginesor gas turbines, for example, with minimal costs for cooling andpurification of said gases.

At the same time, the traditional downdraft gasification process ischaracterized by some disadvantages that have prevented a morewidespread use of that process. Some of the disadvantages of thetraditional downdraft gasification process that have been described inthe technical and scientific literature are: (1) the impossibility ofuse of the downdraft process for processing of plasticizing and cokingfeedstock with high content of volatile components due to thechocking-up of the feedstock in a bunker for drying and low temperaturepyrolysis, which, in turn, results in an unstable gasification processfollowed by its complete shut-down; (2) the impossibility to operatewith feedstock having fine or large fraction, feedstock representingaggregate pressed body, or feedstock with high ash content having lowtemperature of ash melting; (3) the necessity to shut-down the processfor periodic loading or additional loading of feedstock, its manualcrushing and pushing through (which is has been referred to as“poking”), (4) the need for periodic removal of residual ash and/or slagresidue; (5) heterogeneity of v and compositions of the produced gasesdue to the stoppage for loading of the feedstock, which makes it moredifficult to utilize such gases; (6) a low relative productivity ofgasifiers caused by the air flow supply with parameters that do notallow to start the intensive slag formation process; (7) production oftoxic inorganic ash residuals; (8) inability to effectively utilize theheat of the produced gases for improving the gasifier efficiency; and(9) significant heat losses.

SUMMARY

The following is a summary description of illustrative embodiments ofthe invention. It is provided as a preface to assist those skilled inthe art to more rapidly assimilate the detailed discussion, whichensues, and is not intended in any way to limit the scope of the claims,which are appended hereto in order to particularly point out theinvention.

One embodiment of the apparatus of the instant invention comprises anexternal vessel and an external vessel, wherein the internal vessel islocated inside the external vessel, thereby forming a void between theinternal and external vessels. The apparatus also comprises a loadingmechanism with an elongated loading mechanism trunk and a feedstockfeeder for moving the feedstock along the elongated loading mechanismtrunk. The apparatus further comprises a gasifier trunk, a fire chamber,a gas outlet and a slag discharge mechanism.

The operation of the apparatus described above comprises a continuoussupply of feedstock into the gasifier trunk, where the feedstock issupplied under pressure created by the loading mechanism, which causes amovement of the feedstock along the loading mechanism trunk and thegasifier trunk and allows for unhindered passage of the formed gases andresidual carbon through all processing zones followed by the cooling,mechanical crushing and removal of slag.

One embodiment of the new method of the instant invention comprises thesteps of providing a loading mechanism trunk, providing a drying zone,providing a plasticization zone, providing a pyrolysis zone, providing acombustion zone, providing a reforming zone, providing a slag dischargezone, supplying feedstock, forcing said feedstock through said loadingmechanism trunk as well as through each of said drying zone, pyrolysiszone, combustion zone, reforming zone, and slag discharge zone with aloading a loading mechanism that comprises an elongated loadingmechanism trunk and a feedstock feeder. Said method further comprisesthe steps of causing said feedstock to form a plug that substantiallyhermetically separates said drying zone, said plasticization zone, saidpyrolysis zone, said combustion zone, said reforming zone and said slagdischarge zone from the atmosphere and causing formation and separationof steam from said feedstock in said drying zone, causing pyrolysisgases to form in said pyrolysis zone, separating substantially all ofsaid pyrolysis gases from said feedstock in said pyrolysis zone, therebycausing separation of carbon char residue and forming gasificationgases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a schematic depiction of an apparatus pursuant to oneembodiment of the present invention.

FIG. 2 is a symbolic depiction of the distribution of the functionalzones in an apparatus that implements one embodiment of the method ofthe present invention.

FIG. 3 is a flowchart of one embodiment of the method of the presentinvention.

DETAILED DESCRIPTION

The present invention relates to a method and apparatus for processingcarbon-containing feedstock into gasification gases. The followingdescription is presented to enable one of ordinary skill in the art tomake and use the invention and is provided in the context of thisdescription and its requirements. Although the present invention will bedescribed in the context of a method and apparatus for processinghousehold and industrial waste, various modifications to the preferredembodiment will be readily apparent to those skilled in the art, and theprinciples described herein may be applied to other carbon-containingfeedstock, embodiments of the apparatus and modifications of the method.

The present invention allows to process feedstock with variousmorphological structures, fractioned composition, and increased moisturecontent that was impossible to reliably and efficiently process in adowndraft process by the previously-known methods.

Referring to FIG. 1, one embodiment of the apparatus of the presentinvention comprises: external vessel 1, internal vessel 2, fire chamber3, loading mechanism trunk 4, and slag discharge mechanism 5.

The external vessel 1 is preferably made of sheet heat-resistant steelin a form of a cylinder, but it may be made of another heat-resistantmaterial and may have a non-cylindrical shape. Cooling flange 10 isattached to the lower end of external vessel 1 with preferably annularair cooling channel 11. Flange 12 is attached to the upper end ofexternal vessel 1. Gas outlet 13, preferably characterized by arectangular or round cross-section, is positioned tangentially toexternal vessel 1. Gas outlet 13 is intended for discharging producedgasification gases from the apparatus of the instant invention.

Thermal jacket 14 is preferably positioned on the outer surface ofexternal vessel 1. Air channels 15 are formed in thermal jacket 14.Thermal isolation jacket 14 is preferably equipped with external casing16 and landing pads 17. In an alternative embodiment, external casing 16may be fabricated as two cylindrical shells of different diameterconnected together by a rigid concentric bridge and attached to lowerflange 10. Cover 18 is attached to upper Flange 12. Flange 19 ispositioned on the lower portion of cover 18, Air distribution box 20 isattached to the upper surface of flange 19. Flange 19 is coupled withflange 12. Flange 19 is also connected to the upper portion of internalvessel 2.

The body 9 of slag discharge mechanism 5 is attached to lower flange 10.Flange 23 with air cooling channel 24 is positioned above slag dischargemechanism 5. Air channels 48 pass through flanges 10 and 23 and connectair cooling channels 11 and 24.

In this embodiment, internal vessel 2 is characterized by a cylindricalshape and is made of sheet heat-resistant steel. Internal vessel 2 ispositioned inside external vessel 1. Internal vessel 1 and externalvessel 2 are connected through flange 19. Gas channel 26 is locatedbetween external vessel 1 and internal vessel 2.

Cover 21 is connected to the upper portion of internal vessel 2 throughflange 22 with the air distribution shell 20. Fire chamber 3 is locatedin e lower portion of internal vessel 2. Gasifier trunk 8 is locatedinside internal vessel 2. Air supply channels 25 located inside internalvessel 2 connect air distribution shell 20 with fire chamber 3. Pipesmay be used to form air supply channels 25. Blades of turbulator 27 areformed on the outer surface of internal vessel 2.

In the preferred embodiment, fire chamber 3 is molded of heat-resistantsteel. Alternatively, fire chamber 3 may have a welded structure or maybe another suitable manner. Fire chamber 3 is characterized by internalwall 28 and external wall 29. Further, in the preferred embodiment, firechamber 3 is composed of cylindrical shells fixed together by concentricinsertions forming an internal volume—under-tuyere bend 30 connectedwith air distribution shell 20 by air supply channels 25.

Internal wall 28 of fire chamber 3 may have a shape of a truncated conewith a wider diameter at its bottom. Heat-resistant coating may beapplied to the external surface of fire chamber 3. External tuyeres 31may be constructed as nozzles around the circumference of internal wall28.

Internal tuyeres 32 are placed in the central portion of fire chamber 3at an angle to the walls of internal vessel 2. Internal tuyeres 32connected to air distribution shell 20 by air supply channels 25.

Loading mechanism 7 comprises receiving bunker 33, feedstock supplychannel 34 and loading mechanism trunk 35. Loading mechanism may beequipped with piston 36 or a suitable mechanical drive of anotherdesign. In the preferred embodiment, gasifier trunk 8 is placed insideinternal vessel 2 such that the axis of gasifier trunk 8 substantiallycoincides with the axis of loading mechanism trunk 35 and the loweropened edge 4 of loading mechanism trunk 35 is positioned at the levelor slightly below the upper edge of gasifier trunk 8. The diameter ofthe loading mechanism trunk 35 is lesser than the diameter of gasifiertrunk 8.

In an alternative embodiment, a portion of loading mechanism trunk 35that is located above cover 21 can be equipped with a cooler. Gasifiertrunk 8 is formed as a truncated cone widened to the bottom. Degassingslits are preferably formed in the walls of gasifier trunk 8. Thedegassing slits are preferably cut through the entire length of thewalls of gasifier trunk 8, but may leave uncut portions, preferablycloser to the mid-portion of gasifier trunk 8. In the preferredembodiment, degassing slits are wider toward the lower end of gasifiertrunk 8. The diameter of the bottom portion of gasifier trunk 8 islesser than the diameter of internal vessel 2.

In the preferred embodiment, gasifier trunk 8 is reinforced along itslength with steel rings of various diameters attached to the outsidesurface of gasifier trunk 8. Such steel rings serve as rigiditystructures. If the shape of the gasifier trunk is different, therigidity structures will conform to the shape of the gasifier trunk. Forexample, if the gasifier trunk is octagonal, than the rigiditystructures will be octagonal too. In addition, in the preferredembodiment, gasifier trunk 8 is equipped with rigidity ribs positionedon the wall segments separated by the degassing slits.

Damping chamber 37 is formed between internal vessel 2 and gasifiertrunk 8.

Slag discharge mechanism 5 includes cylindrical body 9. Flange 23 isattached to the upper portion of cylindrical body 9. Flange 23 isequipped with air channels 48. Air distribution box 39 is attached tothe inside surface of bottom 40 of slag discharge mechanism 5. Airdistribution box 39 is preferably of a cylindrical shape with bores inits upper portion. A branch pipe of the air supply channel 38 isinserted through the side wall of slag discharge mechanism 5 andattached tangentially to air distribution box 39.

Slag discharge mechanism 5 is also equipped with table 41. Rotating slagscraper 42 is positioned on table 41. Rotating slag scraper 42 isconstructed as a hollow structure with an air- or water-cooling systeminside. Slag scraper 42 is equipped with coolant inlet branch pipe 45and coolant outlet branch pipe 46. Slag scraper 42 is also equipped withbearing unit 4 and mechanical drive 43. Table 41 is attached to body 9of slag discharge mechanism 5.

Flange 23 is a continuation of table 41. Air channels 48 are positionedbetween flanges 23 and 10, air channels 48 connect air cooling channel11 with tray 24 of slag discharge mechanism 5. One or more slagcollection bunkers 47 are attached to the lower surface of table 41.Slag collection bunkers 47 are connected to slag discharge lock channels6.

Operation of the Preferred Embodiment

Feedstock is loaded into the receiving bunker of loading mechanism 33.Then, batches of feedstock are introduced into feedstock supply channel34. Feedstock may be moved by a piston equipped with a drive. Thus,feedstock batches are introduced into a preferably inclined feedstocksupply channel 34 and then into loading mechanism trunk 35. When a batchof feedstock is moved into loading mechanism trunk 35, piston 36 islocated in its upper position. After a batch of feedstock is introducedinto loading mechanism trunk 35, piston 36, driven by its drive, isbrought down into its lower position, thereby moving feedstock downloading mechanism trunk 35. An airtight plug is formed from thefeedstock under the pressure exerted by piston 36 and in conjunctionwith friction forces between the compressed feedstock and internal wallsof loading mechanism trunk 35.

The operation of the drives and the pistons of feedstock supply channel34 and loading mechanism trunk 35 is synchronized. That allows forbatched supply of pressed feedstock in the form of a airtight movableplug into gasifier trunk 8. During the next loading cycle, a new plugthat is formed in loading mechanism trunk 35 pushes the previous onedown into gasifier trunk 8. Because the diameter of the gasifier trunk 8is greater than the diameter of loading mechanism trunk 35, thefeedstock, in the form of pressed airtight plugs, brakes down intosmaller parts that are spread over the entire surface of the upper partof gasifier trunk 8.

Loading mechanism trunk 35 can be equipped with an external coolerprotecting the airtight plug during the operation and especially duringthe shutoffs of the gasifier from drying up or burnout, which can resultin the loss of the plug air-tightness. Gasifier trunk 8 is constructedas a truncated cone widened toward its bottom. The degassing slits,which are also widened toward the bottom, allow to reduce frictionbetween feedstock (as it moves down gasifier trunk 8) and the internalwalls of gasifier trunk 8, which, in turn, facilitates the passage offeedstock through gasifier trunk 8 into the fire chamber 5.

Compacted feedstock in gasifier trunk 8 along its entire length isexposed to the external heat from the walls of internal vessel 2, whichis heated from the outside by hot gases produced in the zone of firechamber 3 and channeled to gas outlet 13 through the gap betweeninternal vessel 2 and external vessel 1. The temperature along gasifiertrunk 8 reaches approximately 700° C. in its lower portion andapproximately 300-400° C. in its upper portion.

Turbulator 27, which consists of a plurality of metal blades attached ina spiral pattern to the external surface of internal vessel 2,intensifies heat transfer from upward flow of hot gasification gases tothe walls of internal vessel 2.

Due to the continuing action of piston 36, feedstock inside gasifiertrunk 8 moves down toward fire chamber 3. As it moves down gasifiertrunk 8, feedstock undergoes changes caused by exposure to the heat.Such low-temperature processing of feedstock can be roughly divided intothree stages: drying, plasticization and low-temperature pyrolysis.Thus, gasifier trunk 8 represents a zone of low-temperatureprocessing—Zone 1. FIG. 2 schematically demonstrates various zoneswithin the apparatus according to this invention:

Zone 1 can be, roughly, divided into three areas:

Area 1.1—feedstock drying zone;

Area 1.2—plasticization zone; and

Area 1.3—low temperature pyrolysis porolysis.

Process steam and pyrolysis gases that contain light tars and carbon areformed by low-temperature processing of feedstock in Zone 1. Such steamand gases enter into the damping chamber 37 through the degassing slitsof gasifier trunk 8. Damping chamber 37 is positioned between gasifiertrunk 8 and internal vessel 2. Process steam and pyrolysis gases thenenter into the zone of the fire chamber 3 through the gap formed by thedifference in the diameters of the lower portion of gasifier trunk 8 andinternal vessel 2. A airtight plug, formed from feedstock in loadingmechanism trunk 35, does not allow the discharge into atmosphere of thesteam-gas mixture formed in Zone 1. The same plug prevents air from theoutside from entering. Light tars and carbon together with pyrolysisgases, which are formed in the zone of the low-temperature pyrolysis(Area 1.3) and which pass through the degassing slits of gasifier trunk8, could block the lower portion of damping chamber 37. However, thehigh temperature of approximately 1300° F. and steam that enters fromthe drying zone (Area 1.1), de-tar the lower portion of damping chamber37, thereby allowing for unobstructed passage of the steam-gas mixturefrom damping chamber 37 into fire chamber 3.

There are no degassing slits in the plasticization zone (Area 1.2). Thatis necessary to ensure that the feedstock, which has changed itsaggregate state from solid to viscous under the pressure of piston 36,is not pushed out at this area through the degassing slits into dampingchamber 37, which could create obstacles for free passage of thesteam-gas mixture.

Air supply channels 25 are positioned in damping chamber 37, on theopposite side of the degassing slits of gasifier trunk 8. Air, heatedfrom the walls of slag discharge mechanism 5, is supplied from the airdistribution shell 20 through air supply channels 25 to internal tuyeres32 and is also supplied through the under-tuyere bend 30 to the externaltuyeres 31.

Steam and/or carbon dioxide can be introduced into the gasifier asadditional oxidizer through steam inlet 49 located in the upper portionof damping chamber 37.

Internal tuyeres 32 are positioned at the level of the lower edge ofgasifier trunk 8. Internal tuyeres 32 are installed at an angle,approximately 45 degrees to the wall of internal vessel 2. The internaltuyeres are attached with plate holders, which also provide support forfeedstock in gasifier trunk 8 to prevent abrupt falling of feedstockinto the zone of fire chamber 3. The plate holders also help to separatefeedstock into segments. That, in turn, facilitates the process ofgasification of residual carbon in the zone of fire chamber 3 because itmakes it possible for the air coming from external tuyeres 31 togetherwith the gases coming from damping chamber 37 to freely penetrate intothe pressed feedstock.

After passing through the zone of low-temperature processing (Zone 1),the steam-gas mixture and residual carbon, which is divided intosegments and partially crushed, enter under action of piston 36 intofire chamber 3, wherein the zone of high-temperature processing (Zone 2)is located. Zone 2 is characterized by temperatures ranging fromapproximately 1300° F. to approximately 2400° F., where steam-gasmixture and residual carbon are subjected to high temperatures, as shownin FIG. 2:

Area 2.1—high-temperature pyrolysis and subsequent gasification zone;

Area 2.2—combustion zone;

Area 2.3—reforming zone.

Fire chamber 3 is positioned in the lower portion of internal vessel 2and consists of a hollow under-tuyere bend 30, comprising the externalwall 28 of fire chamber 3 and internal wall 29 of the fire chamber 3.Air supply channels 25 are attached in the upper part of internal wall29. External tuyeres 31 are located in the middle portion of internalwall 29, along its entire perimeter.

Internal tuyeres 32 are positioned inside fire chamber 3. Externaltuyeres 31 and internal tuyeres 32 form the tuyere bends. Residualcarbon and steam-gas mixture move from damping chamber 37 under theaction of piston 36 along the tuyere bends. The air, heated from thewalls of slag discharge mechanism 5, enters through air supply channels25 into under-tuyere bend 30, where it is further heated while coolingthe metal structure of under-tuyere bend 30.

The heated air enters the combustion zone (area 2.2) of fire chamber 3through external tuyeres 31 at the rate of approximately 30 to 50 metersper second. The heated air is also supplied into the combustion zonethrough internal tuyeres 32, approximately at the same rate. Initially,under the influence of air oxygen in the combustion zone, there occurspractically complete combustion of high-energy gases and tars formed inthe low-temperature processing (Zone 1) as well as partial combustion ofresidual carbon. Due to a significant exothermal effect of oxidativereactions in the combustion zone (Area 2.2), the temperature increasessharply up to approximately 2700-3100° F., which makes it possible touse feedstock with a high moisture content as well as to additionallyincrease the amount of produced gasification gases by means of hydrogasification products.

In turn, increasing moisture content of the feedstock allows to lowerthe temperature in this zone to 1600-2400° F. The high speed of aircoming from the tuyeres greatly intensifies (up to 200%) the combustionof residual carbon directly in front of the tuyeres as compared to theoverall combustion rate in fire chamber 3. That allows to loosen up theresidual carbon bulk present in the zone of the tuyeres bend, to createin the same zone an intensive carbon boiling effect in the gases formedas a result of gasification, to intensify the effect of combustionreactions and primary reforming reactions in the that zone, which, inturn, significantly improves the composition of the producedgasification gases.

The residual carbon, which was not gasified in the combustion zone (Area2.2), descends into the reforming zone (Area 2.3), where it participatesin the secondary reforming reactions that result in a completegasification. In this reforming zone (Area 2.3), the gases and tars oflow-temperature processing, which did not react with air oxygen in thecombustion zone (area 2.2), are finally converted and reduced to thelevel of simple combustible gases under the influence of hightemperatures from hot residual carbon and slag. The reforming reactions,which take place in the reforming zone (Area 2.3), have highlypronounced endothermic character. That results in a decreasedtemperature in that zone as well as in a drop of temperature of theprocessed gasification gases to approximately 1300-1450° F.

The inorganic component of the residual carbon in the combustion zone(Area 2.2) and in the reforming zone (Area 2.3) acts as a sorbent andactively participates in the purification of the produced gasificationgas from hazardous admixtures of heavy metals, sulfur and chlorinecompounds, converting them into inactive insoluble in water form, i.e.,mainly, a complex silicate slag.

The degree of gas purification as well as slag formation temperature inthese zones depends directly upon the ingredients of the inorganiccomponents in the residual carbon. Therefore, the degree of gaspurification as well as the temperature of slag formation can beadjusted using inorganic additives in the feedstock, such as metaloxides, salts and oxide hydrates thereof, silicon dioxide and others.

The slag formed in the combustion zone (Area 2.2) is transferred throughthe reforming zone (Area 2.3) into the slag zone (Zone 3) in a liquid,viscous or solid state depending on the temperatures in these zones,morphological structure and moisture content of feedstock, as well asinorganic feedstock additives and possible additional supply of processsteam into the gasifier. Slag is cooled, and mechanically crushed in theslag zone (Zone 3), with subsequent removal through slag discharge lockchannels 6.

Flange 23 connects slag discharge mechanism 5 with the vessel of thegasifier through the lower flange 10 of the external vessel 1. Throughair channels 48 are positioned between flanges 23 and 10, therebyconnecting air cooling channel 11 and tray 24 of slag dischargemechanism 5. The system of air channels allows, with help of cold airsupplied to the gasifier, reduce the temperatures that affect flanges 23and 10, the body and other elements of slag discharge mechanism 5, aswell as the lower part of external vessel 1, all of which are located inthe high-temperature zone.

The air, heated in tray 24 of slag discharge mechanism 5, is suppliedthrough vertical air channels 15 to air distribution box 20, positionedon cover 21, from which air is directed to the internal and externaltuyeres of fire chamber 3. Body 9 of slag discharge mechanism 5 isattached to table 41 at the point of its transition to flange 23. Body 9has bottom 40. Air distribution box 39 is located on internal part ofbottom 40. Air distribution box 39 is preferably made in a shape of acylinder with concentric bores in its cover.

Air supply channel 38 is introduced through the side wall of body 9 ofslag discharge mechanism 5. Cool ambient air is supplied into thegasifier through air supply channel 38. Air supply channel 38 ispreferably connected to air distribution box 39 at an angle to improveair distribution inside air distribution box 39. Rotating slag scraper42 is positioned on table 41. Slag scraper is cooled from by the airflow air distribution box 39. Slag scraper 42 may be equipped with itsown air or water cooling system, coolant inlet 45, coolant outlet 46,bearing block 44 and mechanical drive 43.

During rotational movements under the action of mechanical drive 43,slag scraper 42 scrapes off, with its toothed edge, a portion of solidslag above, whereas it also scrapes off, with its front sharpened edge,the slag from the surface of table 41, which slag enters in molten form,but subsequently solidifies on the surface of table 41 as a result ofcooling by the air continuously supplied into tray 24. Slag is crushedand, under the action of a centrifugal rotation force of slag scraper42, is thrown to the periphery of table 41, where one or more slagaccumulation 47 bunkers are located. Slag accumulation bunkers areconnected with slag discharge lock channels 6. Thus, slag accumulationbunkers 47 are filled with crushed slag. Subsequently, the upper slidegate of the lock device opens (not shown in FIG. 1) and the slag isdischarged into the lock device, thereby emptying for slag accumulationbunker 47. Then, the upper slide gate closes and the lower slide gateopens (not shown on drawings), thereby emptying slag from the lock. Theslag then is further directed by the transporter into the bunker of slagaccumulation (not shown on drawings). This process allows to dischargethe slag practically without any access of ambient air into thegasifier.

After passing the high-temperature processing zone, the gasificationgases enter into the gas zone—Zone 4, which is located in the areabetween external vessel 1 and internal vessel 2. While ascending fromthe bottom upward through the void between internal vessel 2 andexternal vessel 1 from the lower portion of fire chamber 3 to gas outlet13, the gas flow is cooled down to the temperature of approximately300-400° C. due to the convective heat transfer in the zone oflow-temperature processing (Zone 1) through internal vessel 2. Tofacilitate heat exchange, turbulator 27 is installed in the gas zone(Zone 4).

The gas flow, ascending from the bottom upward, enters into Turbulator27, where it changes direction of its movement while moving in a spiraltrajectory around internal vessel 2. Thereby, both the linear speed andthe turbulence of the gas flow are increased. These two factors,together with the increased heat exchange surface (due to the surface ofthe blades of turbulator 27), significantly improve the heat transferrate between the gases and internal vessel 2, thereby transferring themaximum amount of heat from the gasification gases to the feedstock inthe low-temperature processing zone (Zone 1).

To avoid additional resistance to the flow of the gases coming out ofthe turbulator 27, gasification gas outlet 13 is preferably attachedtangentially with a downward incline to external vessel 1, which,together with high velocity of the gas flow through gas outlet 13,minimizes the deposition on its lower wall of carbon and slag dust thatmay be present in the gasification gas.

Gas outlet 13 has external heat insulation and is connected through aflange joint with the hot cyclone separator that has a thermal isolationcasing allowing to minimize heat losses of the gasification gas throughthe walls of the cyclone separator vessel. The hot cyclone separator isused to clean the gasification gases that exit from the gasifier fromfine-dispersed carbon and slag dust, which is can be collected in thereceiving bin and removed through a lock device.

Gasification gas can be further directed to a system for cooling andfinal purification, where cooling may be done with the production ofprocess steam or hot water, whereas final purification from harmfuladmixtures may be necessary for its further industrial use.

For a better understanding of the instant invention but without limitingits scope, a description of the temperature zones is provided below.

Temperature Zones

Processes of heating, drying, low-temperature and high-temperaturepyrolysis of feedstock take place simultaneously in the apparatus of thepresent invention. In addition, interaction of oxidizing gases withdecomposition products and residual carbon of feedstock takes place inthe apparatus.

Solid household waste (SHW), as feedstock for a gasifier apparatus, isan incredibly diverse and multicomponent composition of organic andmineral components. Table 1 contains data, upon which the followingdiscussion is based.

Organic and mineral components of feedstock are essential for feedstockprocessing. They have a major effect on both the composition of theproduced gasification gases and on the formation of residual slag. Boththe composition and type of mineral components have an effect on theprocessing of feedstock. Two main types of inorganic components aredistinguished: as mechanical admixtures and as components chemicallybonded with feedstock content.

The first and key type comprises an amount of inorganic components thatranges between approximately 6% and approximately 25% of the totalweight of feedstock. This type of components is found in feedstock asmechanical admixtures, such as nonferrous and ferrous metals, ceramics,construction waste, sweepings, glass and other, forming its mineralportion and comprising the following major components, such as: CaCO₃,MgCO₃, FeCO₃, CaSO₄, Na₂SO₄, FeSO₄, FeS₂, SiO₂, silicates with variouscontent of main oxides Al₂O₃, SiO₂, CaO, Na₂O, K₂O and small content ofoxides of other metals.

These components can be symbolically arranged in accordance withdecreasing of their content in feedstock, in the following order:

-   -   SiO₂—dozens of percents;    -   Al, Al₂O₃, MgO, Fe, F₂O₃, CaSiO₃, CaCO₃—percents, dozens of        percents;    -   Cu, Zn, S, TiO₂, FeO, Ni, Pb, Na₂SiO₃, Sn, CaSO₄, MgSO₄, Cl⁻,        S²⁻, Na₂CO₃—percents, tenths of a percent;    -   BaO, ZnO, Cd, NaCl, NaPO₄, MgCO₃, MgSO₄, MgSiO₃, K₃PO₄, CaCl₂,        MgCl₂, K₂CO₃, Cr, Sb, SbO—tenths and hundredths of a percent;    -   NaOH, LiOH, W, V₂O₅, Cr₂O₃, Ni₂O₃, PbO, ZnSiO₃, F⁻, SO₃ ²⁻, Mn,        V, Mo, As, Co, Hg, As₂O₃, BeO—less than one hundredth of a        percent.

The second type of inorganic components comprises components chemicallybonded with feedstock and constitutes a lesser amounts of compounds.This type of mineral components typically constitutes from 0.47% to2.81% of the total weight of feedstock. Some of such components are, forexample, metals and their oxides and salts, which are contained inpaper, cardboard, wood, and dyes, contained in textile waste and polymermaterials.

Zone 1—low-temperature processing zone, with temperatures ranging from:20÷700° C.; this zone provides for drying, destruction andlow-temperature pyrolysis of the feedstock introduced into the gasifier.This zone can be roughly divided by temperature ranges into 3 areas:

Area 1.1—drying zone. The temperature range is 20÷150° C.

Area 1.2—plasticization zone. The temperature range is 150÷350° C.

Area 1.3—zone of the low temperature pyrolysis. The temperature range is350÷700° C.

Area 1.1—drying zone, with temperatures ranging from: 20÷150° C.,located in the upper part of the loading channel, where the followingprocesses take place:

-   -   In the cooled portion of the loading mechanism trunk: compacting        of loaded feedstock and formation of an airtight plug, which is,        essentially, a process of briquetting of feedstock;    -   In the zone warmed by the heat of the gasification gases in the        upper portion of the gasifier trunk: initial warming of        feedstock and evaporation of free moisture;    -   intensive steam formation; drying of feedstock, within which        partial overheating of steam occurs; beginning of the process        for change of aggregative state of fusible elements of        feedstock, softening of local zones in the feedstock bulk.

In the context of drying processes, one distinguishes free moisture,moisture which is mixed with fuel (i.e., moisture, obtained in directcontact with water), and moisture, contained in the structure offeedstock (hygroscopic moisture), which is caused by vapor adsorption.

During the process of heating, the rate of drying quickly increases to aconstant, and then the period of steady drying rate begins, and, afterachieving of a hygroscopic state, the stage of a descending drying ratebegins. The evaporation zone deepens into the bulk of pressed feedstock.At intensive heating of surface beds and enrichment of internal bedswith moisture occur due to moisture evaporation from the surface and itsmovement into the bulk under exposure of hydrothermal conductivity.

During the drying process, the heat conduction coefficient constantlydecreases. The heat-transfer coefficient, starting with a criticalpoint, also dramatically decreases, as the moisture content decreases,which is caused by the deepening of the evaporation area and increasingof thermal resistance of dry outer bed of feedstock.

These processes lead to the deterioration of warming up of the internalbeds of feedstock, which results in increasing times for complete dryingof internal beds of feedstock. Accordingly, the lower limit of thedrying area of the entire feedstock within the gasifier trunk takes ashape somewhat similar to a truncated cone, having its apex in thebottom, as shown in FIG. 2.

Steam, which is formed as a result of feedstock drying, enters thedamping chamber through the degassing slits of the gasifier trunk,where, after making contact with the walls of the internal vessel of thegasifier, it becomes partially overheated.

During the entire drying process, the feedstock contracts; in otherwords, it decreases in volume, and its further warming up leads togreater structural changes.

Area 1.2—plasticization zone, with temperature change ranging from:300÷675° F., is located in the middle warmed portion of the gasifiertrunk, within which the following processes take place:

-   -   the complete drying of feedstock;    -   beginning of processes of decomposition and destruction of        organic polymers;    -   change of aggregative state of fusible materials of organic and        inorganic origin, their conversion into plastic or liquid state;    -   conversion of the entire feedstock into plastic movable mass;        and    -   initial formation of tars and saturated and unsaturated        hydrocarbons.

Thus, at the temperature of approximately 120 C, polyethylene starts tomelt. As the temperature increases, other polymers, representing thefusible portion of the feedstock, start to melt. When the temperaturereaches approximately 200-250° C., all polymers turn into a liquidsubstance, which fills in all voids in the feedstock bulk. At the sametime, the entire feedstock turns into a plastic airtight substance thatslowly moves down the internal space of the gasifier trunk under thepressure applied by the piston of the loading mechanism.

At the temperature of approximately 390° F., mineral colloids transitioninto a vapor phase. The resulting water vapors break through the viscousmass of the feedstock up into the drying zone, and then, together withwater vapors formed in the drying zone, enter into the damping chamber.

In the process of structural changes, which take place in the dryingzone, the entire feedstock contracts significantly and its thermalconductivity increases, thereby facilitating faster warming of theentire mass of feedstock, including its internal portions. However, theinternal portion of feedstock still warms up slower than the externalone. Therefore, the lower boundary of the plasticization zone and itsupper boundary, take a shape of a cone of irregular shape with an apexat the bottom, as shown in FIG. 2.

At the temperature of approximately 480° F. such gases as carbon oxideand dioxide, as well as tar begin to discharge from the feedstock bed.Methane, heavy hydrocarbon gases and hydrogen begin to discharge asheating proceeds. Such gases break through the viscous bulk of feedstockinto the zone of the low temperature pyrolysis. Then such gases flowinto the damping chamber through the degassing slits of the gasifiertrunk.

There are no degassing slits in the area of the gasifier trunk where theplasticization zone is located during the operation of the gasifier.This is done to avoid feedstock being squeezed out into the dampingchamber. However, the steam formed in the upper portion of theplasticization zone enter into the damping chamber through the degassingslits of the drying zone, while the tars and gases from the lowerportion of the plasticization zone enter into the damping chamberthrough the degassing slits in the low temperature pyrolysis zone.

Area 1.3—the low temperature pyrolysis zone, with temperatures rangingfrom approximately 350° C. to approximately 700° C., is located in thelower warmed portion of the gasifier trunk. The following processes takeplace in Area 1.3:

-   -   change of the aggregate state of refractory materials with the        transition thereof into plastic state;    -   decomposition and destruction of organic compounds with the        breakage of covalent bonds in polymers and lattices of organic        compounds;    -   intensive gas discharge;    -   discharge of light tarous substances, solidifying of plastic        material and carbonization thereof, starting with external        layers;    -   transition of the entire bulk of feedstock into residual carbon;        and    -   decomposition of certain organic salts.

The initial decomposition temperature of feedstock is determined mainlyby feedstock's individual properties, although it somewhat depends onthe heating conditions. The higher the content of bonded oxygen that iscontained in the feedstock, the lower is its initial decompositiontemperature.

At the initial heating stages of the feedstock, oxygen-containingcomponents are discharged first from it, and the least oxidized taroussubstances are discharged last. The availability of large amount ofoxygen in the feedstock during its heating leads to an exothermal effectdue to the oxidative reactions that take place. That leads to additionalheating up of the feedstock, which, in turn, speeds up its destruction.Said process is further supported by decomposition of some inorganicsalts, which results in formation of corresponding oxides, in somecases—oxygen and other salts, according to warming up of loadedfeedstock:

Oxidative reactions facilitate the increase of the temperature offeedstock in that zone that results in the discharge of variousdecomposition products, which depend from morphological structure offeedstock, mainly such as: steam, carbon dioxide, carbon oxide, aceticacid, methyl alcohol, formaldehyde, tar, methane, ethane, propylene andhydrogen and also some other decomposition products.

The availability of polymeric materials in the feedstock leads to thecorresponding increase of ethylene and polypropylene yield. At the sametime, polymers are decomposed practically completely without formationof residual carbon.

The aforementioned processes for destruction of feedstock and gasformation lead to significantly decreasing of feedstock amounts andtransition of its structure into dense porous carbon form. As theheating process continues, discharge of tarous substances and otherproducts, condensable at cooling, is practically completed. Although gasformation continues, it continues with a lesser intensity. Products offeedstock decomposition, formed as a result of the low temperaturepyrolysis, enter the damping chamber through the degassing slits of thegasifier trunk. In the damping chamber, such products mix with steamfrom the drying zone and are subjected to further warming up under theaction of thermal radiation from the wall of the internal vessel of thegasifier or from direct contact with it. Tars and particles of residualcarbon being deposited on the walls of the damping chamber, are removedby high external temperatures and steam, which arrives from the dryingzone above.

The draining of the liquid fraction to the center of the trunk and theconical shape of the lower boundary of the zone lying on the solidcarbon residue reduce the possibility of the plastic mass of thefeedstock extruding or of the draining of the liquid fraction throughthe degassing slits of the trunk into the damping chamber.

Zone 2—high-temperature processing zone, with temperatures ranging fromapproximately 700° C. to approximately 1300° C., which is characterizedwith high-temperature pyrolysis of feedstock and further gasificationthereof under exposure of air oxygen and other oxidizers intogasification gas.

This zone is roughly divided by temperature ranges into 3 areas:

-   -   Area 2.1—high-temperature pyrolysis zone. The approximate        temperature range is 700-900° C.    -   Area 2.2—combustion zone. The approximate temperature range is        900-1300° C.    -   Area 2.3—reforming zone. The approximate temperature range is        800-1100° C.

Area 2.1—high-temperature pyrolysis zone, with temperatures ranging fromapproximately 700° C. to approximately 900° C. The following processestake place in this zone:

-   -   final gas evolution process;    -   turning of residual feedstock into solid porous carbon bulk;    -   decomposition and melting of inorganic salts and interaction        thereof with carbon and mineral components of feedstock.

The destruction of the fuel organic mass occurs along with formation ofa small amount of methane, hydrogen as well astracesas traces of otherhydrocarbon gases.

The temperature of 900-1100° C. is the highest temperature at which thecompletion of volatile substances evolution from the solid residualcarbon.

Certain carbonates are melted in this zone: Na₂CO₃—851° C., K₂CO₃—891°C., Li₂CO₃—618° C., and chemically interact with carbon and mineralcomponents of feedstock:

Notably, CO and CO₂ concentrations increase in the produced gases. Inaddition, certain chlorides are melted. For example: CaCl₂—787° C.,NaCl—801° C. Molten chlorides and carbonates can form eutectic mixtureswith more refractory salts, which results in a decrease of the meltingtemperature of the latter. This phenomenon has a significant effect onthe subsequent formation of liquid slag with a decreased meltingtemperature.

Area 2.2—combustion zone, with temperatures ranging from approximately900° C. to approximately 1300° C. The following processes take place inthis zone:

-   -   combustion and heat destruction of the pyrolysis gases with        low-temperature processing of feedstock;    -   combustion of portion of the residual carbon of feedstock;    -   crushing of the residual carbon bulk due to gas-dynamic        processes, conversion of the residual carbon into “boiling” bed        state;    -   separation of the residual carbon;    -   reforming of the combustion gases due to the oxidation of        residual carbon;    -   oxidation processes and reforming reactions of the residual        carbon component; and    -   beginning of the process of the residual slag formation.

The combustion area is the primary gasification zone, wheredecomposition and oxidation of gaseous pyrolysis products occur as wellas intensive interaction of residual carbon, divided into segments andpartially crushed under action of dividing plates positioned in thelower part of the gasifier trunk, together with air oxygen and otheroxidizing gases. Initially only gaseous products are oxidized by the airoxygen, and to a lesser degree their interaction with carbon dioxide andsteam, which is produced during the low-temperature processing offeedstock or supplied to the gasifier.

The limiting factor of gas combustion processes under a specifictemperature is the diffusion rate, and for the residual carbon—thesurface area of heterogeneous phase, the oxygen adsorption rate, and thereaction product desorption rate.

The combustion zone is symbolically identified in the gasification zoneas Area 2.2, whose lower part contains the reforming zone—Area 2.3.Because gas formation processes in these zones are complex andinterrelated, just like the processes of liquid slag formation, it isnecessary to consider them together.

Gasification can be described with simple chemical reactions (1)-(11),which reflect the complex processes occurring in the combustion zone:C+O₂=CO₂+95 407 kCal/mol  (1)2C+O₂=2CO+55 514 kCal/mol  (2)2CO+O₂=2CO₂+135 300 kCal/mol  (3)CO+H₂O=CO₂+H₂+9849 kCal/mol  (4)2CO+2H₂=CH₄+CO₂+59000 kCal/mol  (5)CH₄+2O₂=CO₂+2H₂O+191 759 kCal/mol  (6)C₂H₄+3O₂=2CO₂+2 H₂O+316 195 kCal/mol  (7)C₃H₆+4,5O₂=3CO₂+3H₂O+460 422 kCal/mol  (8)C+H₂O=CO+H₂−30 044 kCal/mol  (9)C+2H₂O=CO₂+H₂−20 195 kCal/mol  (10)C+CO₂=2CO−39 893 kCal/mol  (11)

The combustion process takes place in the upper part of the fire chamberunder exposure to the air oxygen, which is supplied through external andinternal tuyeres that form tuyeres plates, within which the combustionzone is positioned.

For intensification of the gasification process, air is warmed up as aresult of cooling of the elements of the gasifier. In addition, steamand/or carbon dioxide may be injected into the combustion zone at highvelocities. Air injected through the tuyeres at a high velocity (up to50 meters per second) through the tuyeres, intensifies the combustionprocess of the residual carbon of feedstock. That allows to raisetemperatures at the initial stage of jet combustion in the portion ofthe fire chamber that is positioned in the area of the air tuyeres, upto approximately 1500° C., due to a high exothermal reaction effect(1)-(3), together with burning off of high-calorie gases and tars (6),(7), (8), formed in the zone of low-temperature processing of feedstockand in the area of high-temperature pyrolysis, depending on the amountof steam and carbon dioxide.

Air oxygen is practically completely consumed in the oxidation reactionsof the pyrolysis gases and residual carbon with formation of, mainly,carbon dioxide and steam, which later plays the main role in thegasification process. Oxidative gases are also formed. Interacting withresidual carbon, these gases are reduced mainly to simple combustiblegases by reactions (9)-(11).

The increase of the temperature in the combustion zone allows tointensify hydrogasification reactions (9), (10), due to additionalwarming up of the residual carbon and steam, both of which are producedas a result of the oxidizing processes. The increasing temperature inthe combustion zone causes an intensification of the hydrogasificationreaction rates (9), (10) allows to use feedstock with an increasedmoisture content without a need for initial preliminary drying, or toadditionally supply steam from the outside.

Similarly, with exposure to the initial high temperatures, a carbondioxide gasification reaction of residual carbon occurs in the jet (11),which allows to use carbon dioxide supplied from outside as anadditional oxidizer.

Reactions (9), (10), (11) take place mainly at the second stage of thejet combustion process in the combustion zone. These are primaryendothermic reforming reactions. Due to these reaction, the totaltemperature in the lower part of the combustion zone is decreased to900-1100° C. Then, the action of secondary reforming reactions (9),(10), (11) starts in the reforming zone of the gasifier, leading to thegasification of the residual carbon, unreacted in the combustion zoneunder exposure to the residual carbon dioxide and steam, which turnsinto combustible gasification gas.

The high rate of the hot air being injected through numerous tuyeres upto 50,000 kilogram per square meter per hour, intensifies thegasification of the feedstock in the area of the fire chamber locateddirectly in front of the tuyeres. That, together with the increased ofamount of heated air introduced into the combustion zone, allows:

-   -   to cut, break into pieces and loosen the residual carbon, which        comes to the combustion zone from the gasifier trunk as large        sintered porous pieces;    -   to improve the gas-dynamic properties in the combustion zone due        to an intense boiling effect of the residual carbon in gas,        which is a result of gasification, which in turn allows to avoid        the formation of local stagnation areas in this zone;    -   to separate the pieces of residual carbon, where larger and        heavier portions of crushed bulk of the residual carbon descend        into the gasification zone, and smaller portions are gasified in        the combustion zone;    -   to raise the temperature not only in the area where the tuyeres        are located, but also in the entire combustion zone, which        allows to maximally intensify the gasification process and to        increase the degree of tar, acids and complex hydrocarbon        conversion in this zone;    -   to double or triple the total intensity of gasification of the        feedstock, e.g., increasing the throughput from 500 to 1500        kilograms per square meter per hour across the entire        cross-section of the fire chamber;—to produce gases with        improved composition due to their saturation with simple        combustible gases as CO and H₂, which leads to a higher level of        the hydrogasification reaction (9), (10) and carbon dioxide        gasification (11) passing; and

to decrease the ballast content in the total volume of the produced gas,where the ballast is in the form of CO₂, H₂O, O₂, and N₂, as a productof air gasification, which in turn allows to more efficiently use theproduced gasification gases for electricity production and otherpurposes.

The mineral portion of residual carbon is also cardinally changed, bothchemically and structurally, in the gasification zone.

Due to high temperatures, the process of decomposition of salts of themineral portion of the residual carbon that started in the lowtemperature pyrolysis zone is significantly intensified in thecombustion zone. Because of the action of the supplied oxygen, completeor partial oxidation of some metals is possible in the portion of thefire chamber that is located in front of the tuyeres:

Nitrogen N and sulfur S are oxidized to oxides SO₂ and NO_(x) in thesame zone. Their amounts depend on the starting content of said elementsin the loaded feedstock and the amount of free air oxygen in the firechamber.

In the combustion zone, formation reactions of NH₃, H₂S, and HCl andother gases, which are harmful gas components subject to removal fromthe produced gas, take place.

Subsequently, at the second stage of combustion, in the process ofprimary reforming reactions, when oxygen is completely consumed foroxidation, a portion of oxides is reduced to metals and non-metals underaction of the burning hot carbon:

Notably, SO₂ and NO_(x) are reduced to simple elements—S and N₂, whichare further bonded with oxides and metals with the formation ofcorresponding sulfides and nitrides.

Also, the reaction of sulfur dioxide—SO₂ takes place with the formationof hydrogen sulfide—H₂S, which later forms corresponding sulfides byinteraction with metal oxides.

Similarly halogens are bonded with the formation of chlorides andfluorides of various metals.CaO+2HCl=CaCl₂+H₂O

NH₃ can also react with certain oxides and pure metals oxidizing tonitrogen or with the formation of nitrides:2NH₃+3Mg=Mg₃N₂+3H₂2NH₃+2Al=2AlN+3H₂2NH₃+3CuO=N₂+2Cu+3H₂O

In the presence of some unreacted steam in the gasification zone, thedowndraft process, i.e.,—salt hydrolysis, is also possible, but it isminimized due to the activation of the hydrogasification process and thepresence of large amounts of free moisture in this zone.

The entire process continues in the reforming zone in Area 2.3.

Area 2.3—reforming zone with temperatures ranging from approximately800° C. to approximately 1100° C. This zone is characterized with:

-   -   the process of secondary reforming reactions;    -   purification of produced gases from hazardous components;    -   completion of the process of liquid slag formation;    -   processes of final formation of the produced gasification gas        composition.

As a result of processes which take place in the combustion andreforming zones, oxides of various metals containing carbon admixturesand small amount of not decomposed salts as well as reduced pure metalsof minerals portion of feedstock are formed. Depending on the startingcomposition of the feedstock, some amount of metal alloys may be formed,based on iron, copper and silicon.

Exposed to high temperatures, portions of metals as oxides as well aspure metals and salts thereof can turn into a gaseous state. However,most volatile metals and compounds thereof remain in a solid or liquidstate. That can be explained either by an insufficient time they arepresent in the high-temperature zone or by the formation of other lessvolatile compounds, e.g., certain sulfides, silicates and chlorides.

Sulfides, silicates as well as various chlorides formed as a result ofsaid reactions actively participate in the formation of liquid residualslag.

The basic material for the formation of any silicate slag is silicondioxide SiO₂. If there is a lack of it in the mineral component of thefeedstock, it needs to be added during the feedstock preparation.

While passing through the bed of slag being formed, gases produced inthe combustion and reforming zones, are partially purified from thehazardous gas components, mineral dust evacuated with them, solid metalparticles, and a portion of gaseous metals. Consequently, gases withsmall amounts of mechanical admixtures, such as mineral dust, variousheavy metals and other harmful components, enter the fire chamber.

In addition, due to the endothermic effect of reforming reactions,gasification gas at the outlet of the fire chamber has the temperatureapproximately in the range of 700-800° C.

Possible distribution ratios of heavy metals in the slag, in the dustcarried in the produced gas and in the produced gas at the completion ofthe gasifier process are shown the Table 1:

TABLE 1 Content in Metal Content in gas, % evacuated dust, % Content inslag, % Fe 0.02 0.49 99.49 Cr 0.5 4 95.5 Cu 1 5 94 Sn 4 9 87 Zn 4 22 74Pb 5 18 77 Sb 5 17 78 Bi 6 19 75 Cd 12 38 50 Hg 72 12 16

However, the ratios provided in Table 1 depend on the metal activitylevel, their concentration in the residual carbon as well as thepresence of mineral additives in the feedstock in the form of, e.g.,limestone, dolomite and/or base iron ores.

Typically, solid household waste contains significant amount of mineralcomponent. Their concentration increases as the feedstock enters thecombustion zone. That is explained by the gradually decreasing volume ofthe feedstock due to the removal of moisture, gaseous products and tarsfrom it in the low-temperature processing zone. Therefore, the amount ofmineral additives may be reduced or they may not be necessary at all.

It is important that the feedstock contain flux additives for liquidslag. Produced slag should be sufficiently movable and fusible to ensurean uninterrupted operation of the gasifier. The formed slag needs to beable to flow down the channels, which are formed in the residual carbonbulk, into the slag zone, where the slag is cooled with the subsequentmechanical crushing and removal. Slag that is too thick and/or viscouscan make the combustion and gasification zones less penetrable and, as aresult, can slow down or completely stop the gasification process. Italso can substantially complicate its removal from the gasifier.

To facilitate slag passage and removal, special additives, such asfluxes can be used. In case of use of solid household waste as thefeedstock, these additives may be minimal or not necessary at all. Thatis because, mineral components of the feedstock take part, bothchemically bonded with organic components (second group) and as mechanicadmixtures (first group), in the process of residual slag formation.

Small mechanical inclusion of the first group, evenly distributed in theorganic portion of the feedstock, after the pyrolysis zones, areslightly protected by carbon from exposure to high temperatures, and,thus, they are the main source of slag formation.

Large mechanical inorganic inclusions of the first group after pyrolysiszones are also slightly shielded by carbon from exposure to hightemperatures. However, in spite of that, due to their large size andweight, they quickly pass the combustion zone, and enter the lower partof the reforming zone. They are cemented with more fusible finemechanical inclusions, or melted slowly, capturing ash and slagparticles.

In the pyrolysis process, after the removal of volatile components,inorganic compounds of the second group remain in the structure of theresidual carbon, and their melting under due to high temperatures takesplace only after carbon removal because carbon shields inorganiccomponents, hindering their heating and further melting. These mineralinclusions are not the reason of the base slag formation process, and,usually, they remain in solid form.

The increase of the temperatures in the combustion and reforming zonesas well as the availability of large amounts of mineral low-meltingcomponents formed as a result of reforming reactions, allows theformation of eutectic alloys with low melting temperatures andrefractory components. The resulting slag is a free-running ashy masswith solid inclusions of carbon, refractory alloys and particles ofinorganic nature, which did to turn into liquid state, and largeparticles, which did not melt or react chemically.

In the event of accumulation of solid slag in the reforming zone,formation of which may be related to an excessive moisture content inthe feedstock, large amounts of refractory mineral components in thefeedstock or insufficient addition of fluxes, complete or partialclogging of this zone with solid slag is possible.

If that happens, residual carbon exerts pressure upon the slag bulk,where residual carbon is supplied from the gasifier trunk into the firechamber under the action of the loading mechanism. That results in anextrusion of slag from the fire chamber zone into the space of the slagzone, where the slag is cooled, crushed and removed from the gasifier.

Zone 3—Temperatures range in this zone from approximately 300° C. toapproximately 800° C., and the following processes take place:

-   -   slag cooling;    -   mechanical slag crushing;    -   slag removal.

Slag is formed as a result of feedstock processing in the combustion andreforming zones. Slag main components are metal and non-metal oxides:SiO₂, Al₂O₃, Fe₂O₃, FeO, CaO, MgO, Na₂O, K₂O, as well as sulfides,chlorides, fluorides, inclusions of metal alloys and unreacted carbon.Thus, slag is a complex amorphous and crystal form of silicates ofvariable structures with some amount of mechanical inclusions.

Slag enters the slag discharge zone as a liquid, in the form ofindividual solid masses, or, more rarely, in the form of slag bulks.There, it slowly cools down under an indirect action of cold ambient airthat enters into the gasifier. When slag comes to the metal plate table,it cools down from the bottom by the air flow. The liquid fraction ofthe slag solidifies quickly, after which it is cut off by the rotatingslag scraper.

Rotated by the mechanical drive, the upper notched edge of the slagscraper cuts off portions of the solid slag. Slag is crushed, brokendown and removed from the peripheral areas of the table, where one orseveral lock channels are positioned. Then, slag is removed to thetransporter through the slag channels for being discharged from thegasifier. Lock channels allow to perform slag discharge, whileeffectively preventing ambient air from entering into the gasifier.

Zone 4—gas zone with the temperatures ranging from approximately 300° C.to approximately 800° C. In this zone, gas is cooled down from 700÷800°C. to 300÷400° C.

After the reforming zone, the produced gasification gas enters into thegas zone positioned in the space between the external and internalvessels of the gasifier. Passing from the bottom upwards through thespace between the external and internal vessels of the gasifier, the gasflow cools down to the approximately 300÷400° C. due to the heatemission in the zone of low-temperature processing. During that phase,gas “tempering” takes place, which, in the context of the presentapplication, means the finalization of the gas composition.

To speed up heat exchange, a turbulator is installed in the gas zone.The turbulator is a multi-passage tunnel device with spiral channelpositioning. Gas flows passing upwards from the bottom enter into thetunnel device, where it changes its direction while moving in a spiraltrajectory around the internal vessel of the gasifier. The gas flowincreases at a linear rate and becomes turbulent, which improves heatexchange to allow for maximum heat transfer from the gasification gasesto the feedstock in the low-temperature processing zone. Although tar iscontained in the gas in amount of 0.3÷0.5 g/nm³, no tar is deposited onthe walls or on the blades of the turbulator because tar's condensationtemperature is less than 300° C.

Gas flow then passes through the gas outlet into the hot cycloneseparator, where it is cleaned from fine carbon and slag dust, which istypically contained in the gas in the amounted of approximately 3÷10g/nm³. Then, the so removed fine carbon and slag dust is removed fromthe apparatus through the receiving bunker lock and moved to thetransporter for discharge from the gasifier.

Gasification gas is then directed to the cooling and final purificationsystem, where its cooling and purification from the remaining residuesof hazardous inclusions take place, which is typically necessary to makethe gasification gas suitable for power generation or other purposes.

Unless defined, technical and scientific terms used in thisspecification have meanings that should be readily understood by aperson skilled in the art.

Without limiting the above description and possible modifications thatwould be apparent to a person skilled in the art, the following are someof the advantages that may be associated with the methods and apparatusdescribed herein:

The high-velocity hot air introduced through the system of external andinternal tuyeres and caused by it intensification of the gas formationreactions allows to increase the throughput to approximately 1,000-1,500kg/m²/hour across the entire area of the fire chamber. Actual throughputdepends, among other factors, from the morphological structure andmoisture content of the feedstock.

The produced gasification gases have relatively low temperatures(approximately in the range of 300-400° C.), contain practically noacids, the amount of tars is within the range of 0.3-0.5 g/nm³, andamount of fine dispersed carbon and slag dust is within the range of3-10 g/nm³.

There content of heavy metal oxides in the produced gases is relativelylow because heavy metals along with other hazardous components transferinto inactive and insoluble in water silicate form and then they areremoved from the gasifier with slag.

Content of the hazardous gas components, such as NO₂, NH₃, SO₂, H₂S, andHCl, is minimized. At the same time, complex saturated and unsaturatedgaseous hydrocarbons, including dioxins and furans, are practically notpresent in the produced gases.

After being cooled and cleaned, the produced gasification gases mainlyconsist of CO, H₂, CH₄, CO₂ and N₂, where the CO₂ portion is practicallyreduced to zero, and the N₂ content is minimized to the levels ofindustrial use of such gas in standard gas-diesel, gas powered andgas-turbine electro-generating apparatuses, efficiency coefficient ofwhich is twice higher than that of steam apparatuses, which are used inmodern pyrolysis and gasification technologies based on updraftgasification processes.

Without limiting the generality of this invention, the followingbenefits may be derived through the implementation of an apparatusaccording to the present invention:

-   -   ability to use solid household and industrial waste and other        types of carbon-containing feedstock;    -   reduced requirements for and expense of feedstock preparation;    -   no need to perform preliminary drying of the feedstock;    -   the entire feedstock processing (pyrolysis and gasification) can        be performed in the same apparatus;    -   changing of feedstock and discharge of slag are performed        automatically;    -   it is possible to supply an oxygen-steam mix into the apparatus        along with hot air or air-steam mixture, which allows to produce        gases of various quality for various applications; and    -   cooling and purification/cleaning systems use simplified        technologies because of the low level of pollutants found in the        produced gases, thereby reducing the operation costs and        reforming of prices of equipment.

The following examples are provided only to illustrate the presentinvention and should not be construed as limiting its scope.

Example 1: Technological Scheme of an Apparatus for Bed GasificationUnder Pressure

Prior to entering into the gasifier, the feedstock (e.g., solidhousehold waste) is prepared where excessive amounts of inorganiccomponents, especially large fractions are extracted from the feedstock,and then the feedstock is crushed and broken down. Special additive canbe added by means of batchers, depending on the morphological structureof the feedstock, as limestone, dolomite, base iron ores and alsoproducts of finished chemical purification of the gasification gas, suchas, for example, Na₂S, NaCl, NaOH, FeO, Fe₂O₃ and others. Then, thefeedstock passes on the transporter into the bunker of the loadingmechanism and, is transported into the apparatus of processing.

Gasification gases produced as a result of the processing of feedstockwith the temperature at the exit from the apparatus, in the range ofapproximately 300÷400° C., pass through the heat-insulated outlet to thehot cyclone separator, equipped with thermal isolation casing. In thatseparator, gasification gases are preliminary cleaned from themechanical admixtures such as slag and some amount of carbon dust.

The slug formed in the gasifier as a result of processing of feedstockwith the temperatures of approximately 200° C., are supplied to thetransport discharge apparatus through the lock channels and are directedinto the storage bunker, where they are further cooled. The slug dustfrom the hot separator is removed through the storage bunker and lockdischarge channel to the transport discharge apparatus, where it ismixed with the slag from the gasifier and further transported into thestorage bunker.

After the preliminary purification from mechanical admixtures in theseparator, the gasification gases are directed to the first heatexchanger, cooled by cold water, where the gases are cooled toapproximately 40° C. At the same time, cold water, that passes throughthe water treating system, is heated to the temperature of about 60÷80°C. and directed to the second heat exchanger.

The first heat exchanger is equipped with the condensate receiver, wherewater condensed steam, residual tars unreacted in the gasifier, finedispersed slag and carbon dust are accumulated together with other gascomponents. All condensed liquid, viscous and solid components togetherwith condensed water are directed from the condensate receiver through abatcher into the feedstock which are supplied into the gasifier, or passthrough the filter, where excess water is removed from it and directedto the water purification system. Partially dehydrated residue isdirected into the feedstock.

After the first heat exchanger, the partially purified and cooled to thetemperature of 40° C. gasification gases are supplied into the finefilter, where gases are further purified. Wooden chips and/or sawdustmay be used as filtering elements for more thorough cleaning of thegases. After being used in the filter, such filtering elements may beadded to the feedstock. Cleaned and purified gasification gases aredirected to the chemical purification filter, where they are purifiedfrom the residues of hazardous gaseous components, such as HCl, H₂S, SO₂and others.

The filtering element of the filter may represent a porous solidstructure, consisting of iron oxides Fe₂O₃ and FeO that purify gasespassing through them. Sulfur-containing and chlorine-containingcomponents of are bonded on the surfaces of the filtering elements.Cleaning and regeneration of the filtering elements are performed bycyclic passing of NaOH solution through it. The alkali solution containssodium sulfides and chlorides Na₂S, NaCl, as well as some dissolved ironoxides as complex compounds of various composition, such as Na[Fe(OH)₄],Na₄FeO₃ etc.

Upon achieving of the necessary concentration of these substances in theNaOH aqueous solution, the solution is replaced to the new one. The usedsolution together with particles of filtering element dissolved in it,such as Fe₂O₃ and other compounds, is directed through a batcher intothe feedstock and used as an additive. After the chemical purificationfilter, the gasification gas is directed into the gasholder where itscomposition is averaged. Then, gasification gas can be used ingas-diesel, gas powered or gas-turbine aggregates for power generation.

Hot flu gases with the temperatures of approximately 900÷950° C.produced as a result of combustion of gasification gases, are suppliedinto the second heat exchanger, where they are cooled down toapproximately 200÷250° C. At the same time, the water used for coolingis heated to about 60÷80° C. in the first heat exchanger. Depending onthe need and construction of the second heat exchanger, it is possibleto obtain process steam of various parameters and hot water at the exitfor the heat exchanger. The steam portion can be directed to thegasifier through a separate channel as an additional oxidizer.

Variations and modifications and alterations of the above example can bederived from FIG. 3, where the technological scheme of theunder-pressure-bed gasification process is depicted.

Example 2: Comparative Characteristics of Main Utilization Techniques ofSolid Household Waste

For proof of efficiency of the under-pressure-bed gasification processin relation to the prior art technologies, calculations have beenperformed using simplified approximated models. Thus, the results cannotbe considered to be precise reflections of the actual processes. Themain goal of the calculations was to obtain data, based on which onecould perform a comparative analysis of the efficiency of thetechnological schemes of solid household waste utilization.

The algorithm set forth below is a sequence of steps for modeling of thetechnology of bed gasification under pressure. For calculation of allother technologies, the same principles may be used, taking into accountthe differences between process technological schemes. The initialconditions for all technologies are the same—it is the composition ofthe feedstock, its drying and sorting (for all technologies thefeedstock with 10% moisture content and 10% inorganic component isloaded).

1. Feedstock Supplied into the Gasifier.

1.1. The calculation is based on the average morphological structure ofthe solid household waste, as presented in the Table below:

Solid Household Waste Components Content, % News print paper 2.89 Otherpaper 23.19 Food waste 9.02 House waste 3.94 Plastic 16.84 Textile 6.5Wood 4.94 Gum, leather 12.68 Glass 0 Metals 0 Other inorganics or all 20inorganics Construction waste 0 Total 100

1.2. The reference data about element composition of each morphologicalgroup are assumed as follows:

News print Other Food House Gum, other Elements paper paper waste wastePlastic Textile Wood leather Glass metals inorganics building waste C0.366 0.324 0.179 0.232 0.564 0.372 0.412 0.43 H 0.047 0.045 0.025 0.030.078 0.050 0.050 0.054 O 0.300 0.299 0.129 0.175 0.08 0.271 0.346 0.116N 0.001 0.003 0.011 0.009 0.009 0.031 0.002 0.013 Cl 0.001 0.006 0.0040.001 0.03 0.003 0.001 0.05 S 0.019 0.002 0.001 0.002 0.003 0.003 0.0010.012 Moisture 0.25 0.23 0.6 0.45 0.15 0.25 0.16 0.1 Content Ash level0.016 0.091 0.051 0.101 0.086 0.02 0.028 0.225 1 1 1 1 Total 1 1 1 1 1 11 1 1 1 1 1

1.3. Based on the data about the morphological structure and elementcomposition of each morphological group, the element composition of theentire solid household waste is calculated. In subsequent calculation,for simplification, one should not take into account the chlorinecontent in the feedstock:

Content %, without Elements Content, % chlorine C 30.531 30.946 H 4.0944.149 O 15.946 16.163 N 0.739 0.749 Cl 1.341 S 0.329 0.334 Moisturecontent 19.451 19.715 Inorganic component 27.569 27.94 Sum 100 100Organic portion 52.981 52.341

1.4. The calculation of feedstock composition is performed after issorting and drying. For all comparative calculations, an assumption ismade that after sorting the residual inorganics comprise 10%, andmoisture content is 10% after drying:

After Partial Removal of Moisture and Inorganics weight of weightremoved Initial in the moisture and % weight % feedstock inorganicsOrganics 52.34 800 80 800 Inorganics 27.94 427.054 10 100 327.054Moisture 19.72 301.414 10 100 201.414 Content Total 100 1528.4681000.000 528.468

2. Based on the calculated element of the solid household waste,composition the coefficients for the formula of the loaded feedstock aredetermined.

Gross-Formula of the Feedstock Elements Element Coefficients in theGross-Formula C 1 H 1.609 O 0.392 N 0.021 S 0.004 H₂O 0.125

3. All further calculations are performed per 1,000 g of sorted anddried feedstock, i.e. in this case, per 1,000 g of solid household wastewith 10% moisture content and 10% of inorganic components.

4. The quantitative fuel characteristics are calculated based on theobtained gross-formula-element weight in fuel, molecular weight,substance amount, and combustion heat:

Residue Composition (dry) Component % Weight, g C 47.29 472.992 H 6.3463.416 O 24.7 247.04 N 1.14 11.448 S 0.51 5.104 Inorganics 10 100Moisture Content. 10 100

Fuel Substance Amount, mol 39.9087 Fuel Molecular Weight, g/mol22.55147374

5. Calculation of Calorific Value of the Feedstock.

5.1. Calculation of the fire chamber composition without inorganiccomponent and moisture content:

C 59.124 H 7.927 O 30.88 N 1.431 S 0.638 Total 100 Moisture Content. 10Inorganics 10

5.2. Based on the Mendeleyev formula (339C %+1256H %−109,8(O %−S %)=Q)and element composition, the fuel calorific value is calculated. Thecalculations for the fuel organic component, for sorted fuel, and forunsorted fuel are performed in kJ/kg and also in kJ/mol for sorted fuel(the latter is required for further calculation of reaction thermaleffects):

Moisture Inor- Weight of Content. ganics Feedstock fuel combustion heat-1, 26705.99 0 0 800.000 kJ/kg fuel combustion heat -2, 21364.79 10 101,000.000 kJ/kg fuel combustion heat -3, 13977.92 19.72 27.94 1,528.47kJ/kg fuel combustion heat, 602.26 0 0 800.000 kJ/mol

5.3. For further calculation of the thermal effects, the reference dataof combustion heat of the base gases (CO, CH₄, H₂) and carbon (C) areused:

Combustion Heats kJ/mol C 406.8 CO 284 CO₂ 0 CH₄ 808 N₂ 0 H₂ 239.9 H₂O 0

6. An assumption is made in the calculation that the processes ofpyrolysis of loaded feedstock and subsequent oxygen gasification(oxidation), hydrogasification and carbon-dioxide gasification of carbonformed during the pyrolysis occur in the reactor in series.

7. The pyrolysis process is considered as a model reaction:CHONS=C+CO+CH₄+H₂O+H₂S+N₂+H₂Coefficients for this equation can vary, depending on the composition ofthe utilized feedstock. For calculation of the pyrolysis process, thefollowing conditional assumptions are also used:

-   -   CO₂ in pyrolysis stage does not form or is completely consumed        in other reactions;    -   NO, NO₂ and other nitrogen oxide do not form or are consumed in        other reactions;    -   Sulfur forms hydrogen sulfide only; however, under the real        conditions, about 50% of sulfur remains in the residual slag as        sulfides, and a portion of sulfur can pass from the reactor as        sulfur oxides.

7.2. The ratio of the formed CO and H₂O cannot be determined preciselybased on the feedstock composition. These data can be obtained only in apractical way. Thus, such values are set initially in the calculationconditions, as a percent ratio of oxygen turning from the feedstock intoCO and H₂O.

7.3. Similarly, one cannot precisely set the ratio of CH₄ and H₂. Todetermine such parameters, a percent ratio of hydrogen is set, wherehydrogen transfers from the initial feedstock into the products, such asCH₄, H₂O, H₂S, and H₂.

Oxygen Distribution During Pyrolysis Process oxygen in H₂O, % 10 oxygenin CO, % 90

Hydrogen Distribution During Pyrolysis Process hydrogen in CH₄, % 30hydrogen in H₂O, % 4.87 hydrogen in H₂S, % 0.50 hydrogen in H₂, % 64.63

7.4. Based on the element weight in the feedstock and the set conditionson distribution of hydrogen, carbon and oxygen, coefficients inpyrolysis reaction equation are calculated:

Coefficients in the Pyrolysis Equation Coefficient in the SubstanceEquation C 0.527 H₂ 0.520 H₂O 0.0392 CO 0.353 H₂S 0.00404658 N₂0.010372873 CH₄ 0.120666734 sum

7.5. Based on the calculated reaction coefficients, the calculation ofgas and carbon weight and of the amount obtained during the pyrolysisprocess:

Weight, g (taking into Substance Gas Amount, l account loss of C inslag) C 249.17 H₂ 459.02 40.98 H₂O 34.58 27.79 CO 311.27 389.09 H₂S 3.575.42 N₂ 9.16 11.45 CH₄ 106.54 76.1 Sum 924.14 800

8. Oxidation with Oxygen.

8.1. A certain amount of air is supplied into the reactor. Thiscalculation determines an amount of air necessary to be supplied intothe gasifier to remove heat energy in the process of combustion offeedstock portion, which is required for maintaining heat balance of thegasifier.

8.2. To simplify the calculations, an assumption is made that onlycarbon reacts with oxygen. In the real process, initially, thecombustible gases, which are formed during the pyrolysis process, areburned, and the carbon portion is burned in parallel with them. It isalso assumed that the combustion process is completed and no products ofincomplete combustion are formed:C+O₂=CO₂

8.3. The excess of added air may or may not be used in the calculation.

There is no excess air in the case reflected in the table below:

Reagent Supply Oxygen Excess, volume parts 1

8.4. An optional value of weight and amount of spent oxygen, to whichair nitrogen is added correspondingly, is initially introduced into thecalculation:

Gas Weight, g Volume. l O₂ added ((taking into account the excess, ifany) 280.54 196.38 O₂ theoretically required 280.54 196.38 nitrogen fromair 738.76 added air (taking into account the excess, if any) 935.15air, theoretically required 935.15

8.5. Weight and amount of the formed gasification products at thecombustion of the feedstock portion (carbon in this case) and the weightof carbon consumed at that are determined.

8.6. Based on the thermal effect of the carbon combustion reaction, thetotal amount of thermal energy is determined, which is evolved atinteraction of all required air oxygen:

Reaction thermal energy C + O₂ = CO₂, kJ/mol 406.8 Reaction thermalenergy C + O₂ = CO₂, kJ/mol 3566.41

9. CO₂ Conversion—Carbon Dioxide Gasification.

9.1. A portion of formed CO₂ interacts with various solid or gaseouscomponents. For calculation convenience, the CO₂ conversion isconsidered in accordance with the following reaction:CO₂+C=2CO

A conditional parameter is introduced, which can be determined onlybased on the empirical data—coefficient of CO₂ conversion.

CO₂ Conversion in Gasification Process conversion degree 0.5

9.2. Using the conversion coefficient in the calculation, one calculatesan amount of reacting CO₂ and carbon, and amount of formed CO.

10. Hydrogasification.

10.1. Interaction of steam hypothetically takes place with carbonremaining after combustion and conversion of CO₂:C+H₂O=CO+2H₂

This is the main reaction. In the real process, many other products areformed after hydrogasification, but their amount and effect arenegligible.

10.2. The following types of water are considered: first is the moisturecontained in the feedstock; second—added steam or water; third—waterformed in the pyrolysis process. In certain cases, the initial moisturecontent in the feedstock can be sufficient or may exceed what isrequired.

Reagent Supply excess of supplied water or steam, weight parts 1In this case, a calculation of water amount is performed, which water isnecessary to be added.

Gas weight, g volume, l excess of steam + steam, which is added 9.2511.51 for 100% interaction steam, which is added for 100% interaction9.25 11.51 all reacting water 137.04 170.54 all reacting water + excess137.04 excessive moisture content. feedstock 0

11. Gases Produced at the Outlet of the Gasifier.

11.1. The composition of gases produced at the outlet of the gasifier,weight, amount, calorie content and methane equivalent thereof arecalculated. The calculation is based on the composition of the producedpyrolysis gases. Summarizing these data, gasification gases at theoutlet of the reactor are calculated.

Composition of Output Gas Gas Volume Weight % vol. % vol., dry gas H₂629.56 56.21 27.81 27.81 CO 678.19 847.74 29.96 29.96 CO₂ 98.19 192.874.34 4.34 H₂S 3.57 5.42 0.16 0.16 H₂O 0 0 0 N₂ 747.92 934.91 33.04 33.04CH₄ 106.54 76.1 4.71 4.70 Sum 2263.98 2113.247238 100 100 Caloriecontent 8473.03 kJ/m³ methane equivalent 0.24 m³ methane/1 m³ of gasmethane equivalent 0.53 m³ methane/1 kg SHW preliminary dried

12. Energy Losses.

In this case, the following energy losses are considered: 1) endothermicreaction effects; 2) heat loss related to slag removal; 3) gasifierdesign losses; 4) losses associated with hot gases produced by thegasifier; 5) losses associated with steam generation from unreactingwater.

12.1 Thermal reaction effects reference data on combustion heat ofindividual substances are used and calculations of the thermal reactioneffects are performed partially:

-   -   reaction thermal energy of the feedstock pyrolysis; 2)        C+H₂O=CO+H₂; 3) C+CO₂=2CO;

Reaction Thermal Effects reaction thermal energy of residual carbonpyrolysis kJ/mol 5.39 reaction thermal energy C + H₂O = CO + H₂, kJ/mol−117.1 reaction thermal energy C + CO₂ = 2CO, kJ/mol −161.2

12.2. Based on the calculated thermal reaction effects and on the knownamount of the reacting substance, an amount of thermal energy iscalculated, which either absorbed or evolved during these reactions.After that, a summarized (total) amount of thermal energy for allreactions is calculated. In this case, the absorption of a large amountof thermal energy is observed.

heat energy due to the pyrolysis, kJ 212.55 heat energy of the reactionC + H₂O = CO + H₂, kJ −891.52 heat energy of the reaction C + CO₂ = 2CO,kJ −706.62 total thermal effect of reactions, kJ −1385.55

12.3. Thermal Loss Associated with Slag Removal.

Based on the calculated heat capacity, an average morphologicalstructure of slag and on the known amount and temperature thereof, thecalculation of heat loss associated with slag removal from the gasifieris performed.

Heating of Inorganic Feedstock average heat capacity, J/g*K 0.76temperature in the gasifier, ° C. 1100 weight of inorganic portion,entered into the reactor, g 100 Q2 - consumptions for heating ofinorganic feedstock, kJ −104.58

12.4. Losses Associated with the Design of the Gasifier.

The heat loss through the vessel structure of the gasifier depends onmany factors and is extremely complex for a detailed and accuratecalculation. In this case, it assumed that these losses comprise 5%relative to the total energy amount entered into the reactor.

Design Loss, % 5 Q3 - constructional loss, kJ −1068.24

12.5. Heat Energy Removed from the Reactor Together with GasificationGases.

For each gas composition, heat capacity is calculated based on the knownreference coefficients. Using the calculated gas amounts and thetemperature thereof at the exit from the gasifier, one determines anamount of thermal energy removed at their cooling down to 25° C.

Heat of Gasification Gases temperature of gasification gases, ° C. 350gas heat capacity at 600° C. 1.36 gas heat capacity at 25° C. 1.29 heatenergy, evolving with gases, kJ −1008.0

12.6. In case of entry of excess moisture into the gasifier, it is alsonecessary to take into account energy consumption for steam formationfrom such moisture.

There is no water excess in this example.

Steam Formation of Excessive Moisture or Unreacting Water weight ofexcessive water, kg 0 water heat capacity, kJ/kg³K 4.18 thermal effectof phase income, kJ/mol 43.8 energy consumption for water heating from25° C. to 100° C., 0 kJ consumptions for steam formation, kJ 0 Q5 -total consumptions for steam obtaining, kJ 0

12.7. All heat losses of gasifier are summarized.

Total Losses (excluding thermal effects of reactions), kJ −2,180.82Total Losses (together with endothermic effects of −3,566 reactions), kJ

13. Compensation of the Energy Loss.

The compensation is performed due to the thermal energy evolved duringcarbon burning (see 8.6). Thus, it is necessary to supply into thereactor an amount of air for which the amount of the evolved energycorresponds to the amount of the energy losses. Initially, an optionalamount of air supply is assumed (see 8.4). After the calculation of thetotal energy losses, it is possible to determine the equality of theevolved energy after burning and the total energy loss by atrial-and-error method with changing of the amount of supplied air.Thus, the required amount of added air can be calculated.

14. A calculation of the amount of recuperated thermal energy of thegasification gases is performed taking into account that, after therecuperation, gases cool down to 40° C., and the losses due to heattransfer are 10%.

temperature of evacuated gasification gas, ° C. 350 temperature, towhich gases cool down, ° C. 40 gas heat capacity at 600° C. 1.36 gasheat capacity at 40° C. 1.30 coefficient of heat transfer atrecuperation, % 90 Qp2 - recuperated heat, kJ 866.86

15. Generation of Electric Energy.

Two options for electricity generation from gasification gases areconsidered in the comparative calculations:

1) The use of a gas-powered apparatus, with efficiency factor of 38.7%;

2) The use of a steam turbine, with efficiency factor of 20%.

The parameters of the gases being produced allow to consider thepossibility of generating electric energy using the gas-poweredapparatus.

Efficiency factor, % 38.7 amount of thermal energy being obtained fromgases, MJ 19.18 amount of thermal energy being obtained from gases, kWthour 5.33 amount of electric energy being obtained, kWt hour 2.062

16. The recuperation of thermal energy of flu gases after thegas-powered apparatus.

It is assumed in this calculation that from the total energy ofgasification gases:

38.7% converts into electric energy;

41.3% converts into recuperated thermal energy as output hot water orprocess steam;

20% are the reactor design-associated loss and losses associated withthe discharge of flu gases into the atmosphere (in this calculation thetemperature of gases exiting from the heat exchanger is 250° C.).

total amount of thermal energy, contained in the whole gas, kJ 19182.74heat energy after obtaining of electric energy, kJ 7922.47 loss atrecuperation of flu gases heat, % 20 loss at recuperation of flu gasesheat, kJ 3836.55 obtained heat recuperated energy, kJ 4085.92

17. Calculation of Weight Balance.

The input weight is the sum of weights of (a) feedstock being loaded,(b) supplied air, and (c) additionally supplied water or steam. Theoutput weight consists of the weight of the produced gasification gasesand slug weight.

weight balance 2213.25 input weight 2213.25 output weight, g 100 0error, %

18. Energy Balance

Input energy is the combustion heat of the feedstock loaded into thegasifier. Output energy is the sum of combustion heat of all producedgasification gases and all heat loss of the reactor (i.e., heat ofgasification gases, apparatus losses, thermal energy being removedtogether with slag, etc.).

Energy balance difference of Input Produced sum of obtained input andoutput feedstock gases Energy loss energy energy Error, % kJ 21364.7919182.74329 2180.824299 21363.56 1.227 0.0057468The table below illustrates certain advantages of the technology of theinstant invention in comparison to the previously known and usedtechnologies.

Combined technologies Low- High- Gasifiers of (high-temper- temperaturetemperature updraft gasification ature pyrolysis followed pyrolysispyrolysis process (high-tem- by the gasification Downdraft Inciner-chambers chambers (ex- perature gasification of residual carbon in thegasification ators (to 700° C.) ceeding 700° C.) −1000-1300° C.)gasification) process Gas volume, 1 4894 467 610 1680 722 2264composition, CO 8.91 24.64 21.61 26.64 29.96 % CO₂ 11.8 16.49 2.11 5.72.28 4.34 H₂ 16.21 40.08 8.38 26.32 27.81 CH₄ 32.72 11.48 10.56 20.564.71 H₂S 0.21 0.16 N₂ 72.86 1.16 0.89 36.3 0.97 33.04 O₂ 1.76 H₂O 13.5824.51 20.8 17.22 23.22 0 Tarous residue weight, g 200 240 96 200 136composition, C 66 66 66 66 66 % H 7.6 7.6 7.6 7.6 7.6 O 25 25 25 25 25 N1 1 1 1 1 S 0.4 0.4 0.4 0.4 0.4 slag and carbon weight, g 85.5 114.77303.35 73 59.5 100 residue composition, C 19.48 66.55 % H 1.97 0.93 O4.89 2.21 N 0.71 0.31 S 3.47 1.49 Inor- 100 69.48 28.52 100 100 100ganics fin dispersed resi- weight, g 45 135 45 90 135 due, sustainedcomposition, C 70 85 70 70 70 with gases % Inor- 30 15 30 30 30 ganicsNOx high middle middle low low low H₂S,SO₂ high high high high middlelow HCl high middle high high high low Level of gas purification systemhigh high high high high low Used oxidizer air no no air, steam air,steam air, steam level for Sorting yes yes yes yes yes yes preparationof Drying partial partial partial partial partial partial household andindustrial waste Types of used energy apparatuses steam steam steamsteam turbine steam turbine gas powered turbine turbine turbine machineEfficiency factor, % 20 20 20 20 20 38.7 Amount of obtained electricenergy, 0.312 0.34 0.35 0.63 0.491 2.06 kWt/hour Amount of producedthermal energy, 3372 3777 4793 6758 6586 7922 kJ Level of effect onenvironment high moderate moderate moderate low low

While the disclosure above sets forth the principles of the presentinvention, with the examples given for illustration only, one shouldrealize that the use of the present invention includes all usualvariations, adaptations and/or modifications, within the scope of theclaims attached as well as equivalents thereof.

Those skilled in the art will appreciate from the foregoing that variousadaptations and modifications of the just described embodiments can beconfigured without departing from the scope and sprit of the invention.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed herein.

What is claimed is:
 1. A downdraft gasification method comprising thesteps of providing a loading mechanism trunk, providing a drying zoneproviding a plasticization zone providing a pyrolysis zone providing acombustion zone providing a reforming zone providing a slag dischargezone supplying feedstock, forcing said feedstock through said loadingmechanism trunk as well as through each of said drying zone, pyrolysiszone, combustion zone, reforming zone and slag discharge zone with aloading mechanism that comprises an elongated loading mechanism trunkand a feedstock feeder, causing said feedstock being forced through saidloading mechanism trunk to form a plug that substantially hermeticallyseparates said drying zone, said plasticization zone, said pyrolysiszone, said combustion zone, said reforming zone and said slag dischargezone from the atmosphere; causing formation and separation of steam fromsaid feedstock in said drying zone, causing pyrolysis gases to form insaid pyrolysis zone, separating substantially all of said pyrolysisgases from said feedstock in said pyrolysis zone, thereby causingseparation of carbon char residue; and forming gasification gases. 2.The method of claim 1 further comprising steps of causing said separatedpyrolysis gases and said steam to form a mixture; causing said mixtureto move to said combustion zone, burning said mixture in said combustionzone, burning a portion of said carbon char residue in said combustionzone, and using a remaining portion of said carbon char residue forreforming reactions in said reforming zone.
 3. The method according toclaim 2, further comprising a step of supplying air to said combustionzone.
 4. The method according to claim 2, further comprising a step ofsupplying mixture of oxygen and steam to said combustion zone.
 5. Themethod according to claim 3, wherein said air is heated to at least 100F.
 6. The method according to claim 3 wherein said air is supplied at avelocity not to exceed 60 meters per second.
 7. The method according toclaim 1 further comprising a step of causing substantially allhydrocarbons contained in said pyrolysis gases to convert into hydrogenand carbon monoxide while moving through said combustion zone and saidreforming zone.
 8. The method according to claim 1 wherein saidfeedstock comprises mineral components thereby causing said gasificationgases to undergo a purification as they move through said combustionzone and said reforming zone.
 9. The method according to claim 1 furthercomprising a step of adding to said feedstock at least one sorbent. 10.The method according to claim 9 wherein said at least one sorbent is ametal, oxide, salt, or oxide hydrate.
 11. The method according to claim1 further comprising a step of adding to said feedstock at least oneflux.
 12. The method according to claim 9 wherein said at least one fluxis a metal, oxide, salt, oxide hydrate, sulfide, or chloride.
 13. Themethod according to claim 1 further comprising a step of adding silicondioxide to said feedstock.
 14. The method according to claim 1 furthercomprising a step of supplying steam into said combustion zone.
 15. Themethod according to claim 1 further comprising a step of supplyingcarbon dioxide into said combustion zone.
 16. The method according toclaim 1 further comprising a step of causing said gasification gases tomove about at least one of said reforming zone, said combustion zone,said pyrolysis zone, said plasticization zone and said drying zonethereby reducing a temperature of said gasification gases.